The present invention relates to a damped suspension system for reducing transverse swinging of an element depending from an overhead carrier cable while the element is moving forwardly in a straight line, and for limiting the inclination thereof relative to the cable. More particularly, this invention concerns an overhead trolley for conveyance of passengers in cities.
There is the requirement to avoid the inclinations of a cabin of the overhead trolley when moving forwardly in a straight line. This inclination caused, for example, by unilateral load or cross-wind, is very inconvenient for passengers, and moreover, it is undesired because of the resulting necessity to arrange stationary parts adjacent to the straight line track, e.g. stops, at a greater distance to the outline of the cabin. This, however, results in problems since it is difficult to keep the cabin in a vertical position which is necessary for the passengers to get on board. On the other hand, the observance of a certain pivoting angle of the cabin in curves is prescribed. To meet this requirement, there are arranged several stops on the cabin and on the undercarriage. This leads, however, to the difficulty that in the moment of a colliding of the respective stops, a lateral impact acts on the cabin which is transferred to the passengers, which impact must be avoided in consideration of the comfort of the passengers, or at least reduced.
The West German Published Application OS No. 24 38 570 discloses a damped suspension which tries to solve the mentioned problems by providing a blockable device (e.g. hydraulic shock absorber) which cooperates with the cabin and a carrying rod connected to the undercarriage. The operation of the hydraulic shock absorber is caused by a centrifugal measuring device which is arranged within or at the cabin and consists of a pendulum freely moving transversely to the direction of movement, and of two switches. When the conveyor is passing a curve, the pendulum is swinging out according to the centrifugal force and releases the blocking of the device by closing the respective switch. Therefore, a swinging movement of the cabin is obtained which movement is simultaneously dampened by the device. Through this arrangement, a stabilization of the cabin is achieved during a stop of the overhead trolley and during a movement in straight line when a one-sided load or cross wind occur. Furthermore, this reference discloses a further development of the blockable device as mechanical drive which is controlled by a centrifugal measuring device wherein a pressure scale is interposed and thereby causing a swinging of the cabin during the movement in a curved track. Therefore, a colliding of the stops on the cabin and on the carrier can be kept within the scope of the admissible end acceleration of 1 m/sec.sup.2.
This principle is rather sound, however, the structural solutions for carrying out the principle into effect are rather complicated and expensive. They require the use of a centrifugal measuring device, a control line and magnetic valve according to FIG. 1 of the published application; and of a centrifugal measuring device, pressure scale, hydraulic lines, and a mechanical drive, according to FIG. 3 of the application.
This is clearly undesirable, not only because the increased manufacturing expenses reflect unfavorably on the stability of the machine, but also because the relative complexity of these constructions tends to make them susceptible to malfunction which in turn undesirably increases maintenance expenses.